So here’s something that Apple’s GUI gurus didn’t get right: How to save draft email in the iPad/iPhone’s Mail application.
Stop writing. Hit “Cancel” (1), yes, I know, that doesn’t feel right or comforting. But then up pops the option to “Save” (2) your email. You’ll then find it in your “Drafts” (3) folder.
If you have multiple email accounts, you may need to back out of “All Inboxes” and then scroll down to the specific email account you were sending from — before navigating into the appropriate “Drafts” folder.
Short cut to retrieve a draft: As long as you don’t restart your iPhone, there’s a short-cut to retrieve the last last draft you saved: Simply press and hold the button to compose a new email — until you draft reappears.